MEAN FIELDS - EXPLICIT DISPERSIVE AND RETARDATION PROPERTIES OF THE DYNAMICAL POLARIZATION POTENTIAL WITHIN A SIMPLE-MODEL

The dynamical polarization potential corresponding to a simple and tra ctable, but physically meaningful, two-channel model is derived and ex amined, with particular attention to its analytic properties. This ena bles us to illustrate explicitly the emergence of the general dispersi ve and retardation features expected from the imposition of causality. The energy dependence of the potential, and the associated nonlocalit y in time expressed by its Fourier transform, are explored. A new theo rem is proposed for the asymptotic behavior of the Fourier transforms.